Fender EC Tremolux tube question

So I traded for this amp recently. Came to me with all stock tubes. I messed around, tried other tubes. Ended up swapping all of them for something else, excepting (I think) the phase inverter. It sounded quite good to start, sounds even better now.

I never use the tremelo, so didn't realize until today that it has mostly disappeared. Very faint, compared to how it sounded when I tried it out, with the stock tubes. (Note: There is only one knob for trem - speed. Intensity must be set somewhere in the circuit.)

Do any of you schematic reading folks have a clue as to how I managed to diminish the trem, and how I might correct it?

Since nobody with more experience has answered, I'll take a guess at it.

I can't find the schematic for that amp on the Fender website, so it appears that you have to email or call them for a copy. Given that by Fender's description it appears to basically be a tweed Deluxe with tremolo added, and has one extra preamp tube from the specs, I would suspect that it would be the tube closest to the power tubes. Generally that would be the phase inverter, which you said you don't think you changed, but in the tweed Deluxe and early Tremolux (which are both cathode biased) the PI is half of V2 and there is no V3. When you swapped tubes, did you use 12AX7s in the V2 and V3 positions? If you went to a lower gain tube (12AY7, 12AT7, 5751) anywhere other than V1 that may affect the strength of the trem.

With a tweed Vibrolux, brown, or black Princeton (which are fixed bias) they varied the bias to the power tubes and if the power tubes are biased too high the tremolo gets weaker. I don't know if there is a way to do bias varied trem on a cathode biased amp. If there is, then I would try putting back your old power tubes to see if anything changes. Maybe your new power tubes end up biasing hotter and are diminishing the amount of tremolo. Make sure to change only one preamp tube at a time, or just the two power tubes to try to troubleshoot it or you won't know where the problem is.

Basically, I'd try swapping in one of the original tubes into V3 first, if that doesn't change put your new tube back in and try swapping V2 on the chance that it affects something since that tube is connected to the power tubes on the fixed bias models, and then try swapping back to the original power tubes.

V1 (12AX7) is the first preamp gain stage, and only half of the tube is used. Half of V2 (12AX7) is the tone stack recovery (second stage), and the other half is the phase inverter (PI), which is a concertina style inverter section. V3 and V4 (6V6) are output tubes. V5 is the rectifier, and V6 (12AX7) is the Vibrato effect tube.

The amp needs to be re-biased if the Output tubes are changed, it is a fixed bias type with an adjustable bias pot, it is not Cathode biased like a 5E3.

Interesting stuff. I have to check that V6 tube. I did rebias after changing power tubes. It is bias vary, so it's possible that did it right there. Even though I did bias it to the right range for the B+ voltage.

I've replaced all of the tubes in my EC Tremolux. At the moment it has Tung Sol RI 12AX7s and 6V6s (the latter professionally biased), and I just replaced the 5Y3 that died with a NOS GE tube. It's a great amp for a range of live situations. I've swapped several speakers in and out, including Eminence Stonehenge and C.Rex and Celestion V30, but the stock G12-65 is back in it now. I prefer it and the V30. I tend to run the volume at 3-6 and tone at 8-9 with either a boost pedal or a low gain OD (Rockett Blue Note or Mad Professor SHOD) always on. That arrangement gives me enough volume in a band situation, even unmiked, and cleans up beautifully from the guitar volume control.
I'm mainly a blues and roots/Americana player using Strats, but my LSL Mongrel (Tele pickups) and Gibson LP Jr are right at home with the Tremolux, too. The light weight is a blessing.
I did not get a schematic in my manual, so if anyone can post one I'd be grateful. Thanks for the tube breakdown info in the meantime!

I was puzzling over why only have of the 12AX7 in V1 is used here, but now I suspect that it's because there is only one channel - the other half would be used traditionally as the first gain stage of the second Deluxe channel. Sound right?

I was puzzling over why only have of the 12AX7 in V1 is used here, but now I suspect that it's because there is only one channel - the other half would be used traditionally as the first gain stage of the second Deluxe channel. Sound right?

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More than likely it's just a decision made by amp designer that he didn't need the full 100% gain both triodes of the 12ax7 would provide. He probably just said that it OD's to easy, let's just use 50% of v1 so it will stay a little cleaner.

I'm loving that stock speaker. This is such an interesting amp. Looks tweed deluxe but sounds different. I use mine always with TIM clean boost in front. It turns out to be maybe the best sounding amp for strats I've played yet. Such a fat, rich sound with the strat.
MD

More than likely it's just a decision made by amp designer that he didn't need the full 100% gain both triodes of the 12ax7 would provide. He probably just said that it OD's to easy, let's just use 50% of v1 so it will stay a little cleaner.

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I don't think so in this case. This amp is based on the 5E3, which has two channels served by the two halves of V1. Since the EC Tremolux deletes one channel, it appears to leave half of V1 unused. At least that makes sense to me, since I don't think Fender started with a blank slate here.

I don't think so in this case. This amp is based on the 5E3, which has two channels served by the two halves of V1. Since the EC Tremolux deletes one channel, it appears to leave half of V1 unused. At least that makes sense to me, since I don't think Fender started with a blank slate here.

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This sounds more likely, especially if they claim that V6 is for the tremolo. Without a schematic it's hard to say, and since they added an extra tube I'm guessing that the tremolo uses the entire additional preamp tube instead of half of it like on a later Princeton (single channel, two preamp tubes). That would leave you with either half of the PI or half of V1 unused like you mentioned because the Deluxe has two channels and the second half of V1 on the Deluxe was the first gain stage of the second channel and half of V2 was recovery for both channels if I remember correctly.

I used JJ 12AX7 in all the sockets and Tungsol 6V6 in power and NOS Tungsol for the rectifier. Everything works great and sounds so much better than the stock tubes. The tremolo on the amp is not that great since you cannot control the intensity. I just turn it off.

The G12-65 has been a revelation to me. I had imagined it being dark and sterile but it's nothing like that. I find it rich sounding and while seems to cut the really high end, it has a beautiful, controlled brightness to it, both clean and dirty, at least in this amp.

I love this Tremolux .

Mine needs power tube replacement, as lately it presents random volume jumps and some extrange fuzzy/rattling noises... It's the first time I have to replace tubes in an amp, but AFAIK those are warning signs.

I bought it second hand, it came with Groove Tube branded EHX 6V6GT (factory originals I guess) and three 5751 preamp tubes. Really sweet.

Changing the middle preamp tube changes the tremolo depth. Right now I have a Chinese 12AX7 for a deep pulsating effect.

V1 (12AX7) is the first preamp gain stage, and only half of the tube is used. Half of V2 (12AX7) is the tone stack recovery (second stage), and the other half is the phase inverter (PI), which is a concertina style inverter section. V3 and V4 (6V6) are output tubes. V5 is the rectifier, and V6 (12AX7) is the Vibrato effect tube.

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Nope, nope and nope!

V1 is used completely - half for the instrument inputs, half for the mic inputs. Stock in the Tremolux is a 12AY7.

V2 is the tremolo tube. Both halves are used. A 12AX7

V3 is the driver tube. Both halves. A 12AX7

V4 and V5 are the power tubes. 6V6's

V6 is the rectifier. A 5Y3

Everybody have that now? LOOK at the 5E9-A schematic - use Google, it's the FIRST one that pops up.

Since I've never had aspirations of being the "next EC", I'll probably never buy that amp. Like the song lyrics go: "...I've gotta be me..." so, generic Fender works just fine, there's no snobbery in my gear collection.